This invention is directed to improving properties of carbonous materials such as coal and oil shale and, in particular, to improving yields and physical characteristics of products derived therefrom.
Much work has been done in recent years to make useful liquids and gases from carbonous materials such as coal and oil shale. Various types of liquefaction processes have been developed such as solvent refining, direct hydrogenation with or without a catalyst, catalytic and non-catalytic hydrogenation in the presence of a non-donor solvent, and catalytic and non-catalytic liquefaction by the donor solvent method. Exemplary of a hydrogen donor solvent liquefaction process is that disclosed in U.S. Pat. No. 3,617,513.
In an effort to increase liquefaction yields, a number of ancillary processes have been developed. Such processes include the pretreatment of coal prior to a liquefaction process or post-treatment of products derived from a liquefaction process, i.e., liquefaction distillates, coal liquids, and coal bottoms. Exemplary of pretreatment processes in U.S. Pat. No. 4,092,235, which discloses acid-catalyzed Friedel-Crafts carbon-alkylation and carbon-acylation of coal to increase the yield of products from coal liquefaction. The introduction of aliphatic hydrocarbon radicals or acyl radicals, including carbon monoxide, into the coal structure, is believed to permit a greater quantity of the coal to undergo liquefaction at suitable liquefaction conditions. The alkylation and acylation reactions, which may be conducted in the presence or absence of added or extraneous catalysts, take place at carbon sites.
Other processes have also been proposed to increase liquefaction yields and to improve the properties of products therefrom. For example, copending U.S. application Ser. No. 62,809, filed Aug. 1, 1979, now U.S. Pat. No. 4,259,084, and Ser. Nos. 69,059; filed Aug. 23, 1979, now U.S. Pat. No. 4,259,167; 69,061, filed Aug. 23, 1979, now U.S. Pat. No. 4,259,072; 69,064, filed Aug. 23, 1979; and 69,066, filed Aug. 23, 1979, now U.S. Pat. No. 4,259,173, disclose processes for treating the weakly acidic protons of coal and coal products by oxygen-alkylation and oxygen-acylation employing a phase transfer reagent and an alkylating or acylating agent.
While these processes have met with varying degrees of success, there is still a need in the art to develop more efficient methods for improving liquefaction yields and improving the properties of coal products.